1. Field of the Invention
The present invention relates to a magnetic core assembly used for a transformer or an electric motor, particularly to the magnetic core assembly having a bobbin and a mounting board thereof.
2. Related Art
A conventional transformer is shown in FIG. 7. As illustrated in the drawing, a transformer has a pair of cores 100 and a cylindrical bobbin 200. Each core 100 has an E-shaped section, and the bobbin 200 has a primary coil 301 and a secondary coil 302 which are wound thereon. The bobbin 200 has a through hole in which a central projection 101 of each of the E-shaped cores is inserted, so that the bobbin 200 is sandwiched between the E-shaped cores.
As shown in FIG. 7, the primary coil 301 and the secondary coil 302 generate magnetic flux L1 defining an ellipsoidal contour. The magnetic flux L1 is not along the cores 100, because the cores 100 have a rectangular shape. That is, the cores 100 have corners excessively sharp for the magnetic flux, at which the magnetic flux L1 partially expands outside cores 100. Furthermore, the cores 100 cover the coil bobbin 302 only partially, so that the magnetic flux L1 extends externally from the cores 100, decreasing efficiency in energy.
The leaked magnetic flux L1 generates radiant noises which may cause wrong operations of electronic circuits such as a switching circuit disposed near the transformer and a decreased power efficiency of the transformer itself. Such radiant noises are disadvantages to meet safety standards of EMC (Electromagnetic Compatibility) and EMI (Electromagnetic Interference) in respect of electric instruments having such transformers. Thus, some additional structures like a shield are necessary for circuits near the transformers so as to meet the standards of EMC and EMI. Accordingly, parts of the circuits increase in number to solve the noise problem and to meet the safety standards of EMC and EMI, increasing a manufacturing cost with an additional design work thereof.
In view of the foregoing situation, an object of the invention is to provide an improved magnetic core assembly, particularly a magnetic core assembly having a bobbin wound with coils and a mounting board for the core assembly. The magnetic core assembly can easily solve noise problems and decreases parts required for noise countermeasures, achieving a lower manufacturing cost including design thereof and an easy certification acquisition of the safety standards. Furthermore, the magnetic core assembly can improve power efficiency.